Al-Adab Al-Mufrad #642

Abu Sa'id al-Khudri reported that the Prophet, may Allah bless him and grant him peace, said, "If any Muslim does not have anything to give as sadaqa, he should say in his supplication, 'O Allah, bless Muhammad, Your slave and Your Messenger and bless the believers, both men and women, and the Muslims, both men and women.' That will be sadaqa for him."